1. Field of the Invention
This invention relates generally to energy absorbers and more particularly to a syntactic foam energy absorber of the type that can be used to protect underlying structures including motor vehicles.
2. Description of the Related Art
Presently vehicles such as automobiles are required to have energy deflecting members which protect the passengers and the vehicle itself from the effects of collisions. Among the present conventional forms of protection are rigid metal and plastic bumpers. Moreover, side doors have included rigid metal members which are intended to reduce intrusion of another vehicle into the passenger compartment during a crash, but which do not effectively absorb a sufficient amount of energy. In addition, the instrument panels have been padded with foam plastics which cushion the force exerted on vehicle occupants during secondary impacts with the panel. All of these approaches have their advantages and some shortcomings in certain circumstances.
To date, conventional syntactic foam has been proposed for structural applications. Such foams have included hollow plastic or ceramic microspheres held together with a binder. Some examples of structural foams are given in the Encyclopedia Of Composite Materials and Components, copyright 1983, by John Wiley & Sons, page 548. It has been suggested generally that syntactic foams might have application in the automotive industry in WARDS Auto World, March 1989, pages 87 and 88. However, the previously known syntactic foams are believed to be too brittle, are susceptible to fracture over a narrow range of stress, and are not able to absorb energy over a sufficiently wide range to be effective for applications including the ones indicated herein.